Performance inefficiency is a critical challenge facing the construction industry. Despite the efforts made in the existing body of literature, an integrated theory of performance assessment facilitating a bottom-up understanding of the dynamic behaviors, uncertainties, and interdependencies between the constituents in construction projects is still missing. The traditional paradigm for performance assessment is mainly based on a reductionism perspective, in which construction projects are identified as monolithic systems. However, complex construction projects are systems-of-systems. Systems-of-systems have unique traits that are different from those of monolithic systems. Failure to investigate construction projects as systems-of-systems has led to theoretical and methodological limitations in the creation of integrated tools and techniques for better assessment of performance in complex construction projects. To address these theoretical and methodological limitations, a system-of-systems framework is proposed as a theoretical lens and methodological structure toward creation of tools and techniques for integrated performance assessment of complex construction projects. Two principles (i.e., base-level abstraction and multi-level aggregation) are used to develop the proposed framework. The proposed framework facilitates a bottom-up evaluation of the dynamic behaviors, uncertainties, and interdependencies between the constituents in construction projects. The capabilities of the proposed framework show its potential in addressing the limitations pertaining to the traditional frameworks for performance assessment. Hence, it can be adopted and tested by researchers to advance the body of knowledge and create integrated theories of performance assessment in complex construction projects.